Green fluorescent protein, received via DNA from father, which had been implanted with glowing sperm-creating cells from a flourescent mouse (2004)

What can we learn?

University of Pennsylvania researchers figured out how to maintain and grow glowing, sperm-creating stem cells from genetically modified fluorescent mice.

The team then implanted the cells into infertile mice, which "miraculously" fathered three of the pups pictured--and the offspring of the lucky mice "men" glowed green under ultraviolet light, tipping the scientists off to their success.